1. Field of the Invention
This invention relates to a solid propellant, particularly a flowable solid propellant.
2. Description of Related Art
Today, most rocket propulsion falls into one of two categories, namely solid or liquid systems. Solid motors have the advantage of being low cost and storable. These rockets also have their disadvantages such as lower volumetric propellant loading and lack of ability to vary the thrust profile after the motor is manufactured. Liquid engines have the advantage of higher efficiency, higher volumetric loading of the propellants and throttleability. However, the liquid systems suffer most from their high cost, complexity and lack of storability.
There is thus a need for a new propellant that overcomes the above prior art shortcomings.
There has now been discovered a propellant that is storable, flowable, of high volumetric loading and throttleable.
Broadly the present invention provides a method for preparing a flowable solid propellant comprising,
a) adding liquid oxidizer to a tank and
b) adding pellets of cross-linked hydrogel polymer to the liquid oxidizer to form a mixture in the tank so that at least some of the liquid oxidizer is absorbed into at least some of the pellets to form flowable combustible pellets.
Also provided is a propellant comprising, cross-linked hydrogel polymer pellets and a liquid oxidizer absorbed in the pellets to form a flowable combustible propellant.
By xe2x80x9cpropellantxe2x80x9d as used herein, is meant the overall mixture in the tank, e.g., of polymer pellets and liquid oxidizer (whether absorbed into the pellets or not, including between them) and additives if any, e.g. of metal, all of which add up to 100 wt.% (of the propellant).